Innovative fruit tree architecture as a nexus to improve sustainability in orchards

The height and width of trees influence all cultural practices in orchards, from crop load control and pruning to crop protection. Many different shapes and planting configurations are used worldwide in fruit growing. Even though genetic characteristics determine tree vigour, the shape and size of fruit trees is strongly affected by cultivation techniques. Trees do not require a second level of structure (large branches) which actually results in unfavourable big canopies. There are various ways to “de-structure” tree canopies and eliminate large branches, such as splitting the single tree into two or more smaller leaders, and applying summer pruning. Unlike standard canopies with single leader training (e.g., spindle, solaxe), multi-leader tree training naturally forms a two dimensional fruiting wall with short limbs and consequently provides several opportunities to decrease dependence on chemicals while maintaining the necessary high fruit yields and quality of modern orchard systems. Tunnel sprayers, mechanical thinning and pruning, multi-task nets, and solid set canopy delivery system (SSCD) spraying are among the possible options offered by such thin, short fruit trees. When multi-stemmed trees have to be formed in the orchard, in the first 2-3 years they require more hand labor and produce less fruit, but soon they achieve similar production volume of standard orchards with less work. This training implies changing tree spacing and the parameters of planting systems from a few rows of large, tall trees to many rows of short, narrow trees in which fruiting wood is kept close to the trunk (centripetal fruiting). In the end, changing tree architecture can greatly help to improve the economic and ecological sustainability of the fruit industry. New ultraNDASHnarrow viticulture-like pedestrian systems are the next step toward platform-free orchards to achieve further simplification of most cultural practices and harvest.